In the field of clock adjustment devices, there have been many previously-developed devices for facilitating clock adjustment. Many of these devices are for applications having a large number of clocks, such as a school or office building. For example, one system for resetting a large number of clocks involves the use of an additional stepper motor installed in each clock. When the stepper motor receives appropriate signals over a power line, it operates to cause the clock to read a certain time. The signals sent over the power line are at a frequency different from the rated alternating current (AC) power line frequency. Additional signals are then used to cause the stepper motor to set the clock to the correct time. If a clock does not contain the stepper motor, it cannot be reset by this system.
Another method that has been used to set clocks uses a high-frequency signal that is transmitted over the AC power line to the clock. The high-frequency signal is different from the AC power line frequency. The clock contains a control device that receives the high-frequency signal and controls the clock motor such that the clock may be reset to a new time. In order for the clock to be responsive to the control signal it must contain the control device.
Each of these and other previously developed methods and systems for controlling clocks suffer from the same problem; that is, in order for the method to work with a given clock, a special device or control must be installed in the clock.